[Player] Add AI Pathfinding on a 2D grid to the player character

Assets/External/AstarPathfindingProject/ExampleScenes/ExampleScripts/ObjectPlacer.cs

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+using UnityEngine;
+using System.Collections;
+
+namespace Pathfinding.Examples {
+	/// <summary>Small sample script for placing obstacles</summary>
+	[HelpURL("http://arongranberg.com/astar/docs/class_pathfinding_1_1_examples_1_1_object_placer.php")]
+	public class ObjectPlacer : MonoBehaviour {
+		/// <summary>
+		/// GameObject to place.
+		/// When using a Grid Graph you need to make sure the object's layer is included in the collision mask in the GridGraph settings.
+		/// </summary>
+		public GameObject go;
+
+		/// <summary>Flush Graph Updates directly after placing. Slower, but updates are applied immidiately</summary>
+		public bool direct = false;
+
+		/// <summary>Issue a graph update object after placement</summary>
+		public bool issueGUOs = true;
+
+		/// <summary>Update is called once per frame</summary>
+		void Update () {
+			if (Input.GetKeyDown("p")) {
+				PlaceObject();
+			}
+
+			if (Input.GetKeyDown("r")) {
+				StartCoroutine(RemoveObject());
+			}
+		}
+
+		public void PlaceObject () {
+			Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
+			RaycastHit hit;
+
+			// Figure out where the ground is
+			if (Physics.Raycast(ray, out hit, Mathf.Infinity)) {
+				Vector3 p = hit.point;
+				GameObject obj = GameObject.Instantiate(go, p, Quaternion.identity) as GameObject;
+
+				if (issueGUOs) {
+					Bounds b = obj.GetComponent<Collider>().bounds;
+					GraphUpdateObject guo = new GraphUpdateObject(b);
+					AstarPath.active.UpdateGraphs(guo);
+					if (direct) {
+						AstarPath.active.FlushGraphUpdates();
+					}
+				}
+			}
+		}
+
+		public IEnumerator RemoveObject () {
+			Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
+			RaycastHit hit;
+
+			// Check what object is under the mouse cursor
+			if (Physics.Raycast(ray, out hit, Mathf.Infinity)) {
+				// Ignore ground and triggers
+				if (hit.collider.isTrigger || hit.transform.gameObject.name == "Ground") yield break;
+
+				Bounds b = hit.collider.bounds;
+				Destroy(hit.collider);
+				Destroy(hit.collider.gameObject);
+
+				if (issueGUOs) {
+					// In Unity, object destruction is actually delayed until the end of the Update loop.
+					// This means that we need to wait until the end of the frame (or until the next frame) before
+					// we update the graph. Otherwise the graph would still think that the objects are there.
+					yield return new WaitForEndOfFrame();
+					GraphUpdateObject guo = new GraphUpdateObject(b);
+					AstarPath.active.UpdateGraphs(guo);
+					if (direct) {
+						AstarPath.active.FlushGraphUpdates();
+					}
+				}
+			}
+		}
+	}
+}